Title

13 Sodium Bisulfite Pump Rotation

Sodium bisulfite is injected to the chlorine contact chamber (CCC) effluent prior to discharge for dechlorination purposes. The sodium bisulfite is injected via metering pumps.  The application rate for chemical injection is controlled by a compound loop control system:  chlorine residuals are measured and the sodium bisulfite dosage is automatically adjusted in order to maintain a set point parameter.  This parameter is just under the maximum allowable chlorine concentration limit of 0.1 mg/l. 

SOP Identification Number
SOP Identification Number:
1302_SodiumBisulfitePumpRotation
Purpose and scope
Purpose and scope:

Dechlorination is necessary in order to reduce the toxic effects of chlorinated effluent on aquatic life in the receiving water body.

Definitions
Definitions:
  • SBS: Sodium bisulfite 
Health & Safety Warnings
Health & Safety Warnings:

See MSDS information for sodium bisulfite.

Cautions
Cautions:

There should be enough turbulence at the point of application to ensure complete mixing.

Potential Interferences
Potential Interferences:

Sodium Bisulfite Pump 1302PMP/MTR3100 is labeled P211 and Sodium Bisulfite Pump 1302PMP/MTR3200 is labeled P-212 on the SCADA screen display.

 

Personnel Qualifications
Personnel Qualifications:

Operator I, knowledge of disinfection system controls and permit requirements.

Equipment, Supplies, Required Tools
Equipment, Supplies, Required Tools:

Monitor supply of sodium bisulfite.  The chemical is commercially available in 25% and 38% concentrations.

Quality Control/Quality Assurance Activities for the Procedure
Quality Control/Quality Assurance Activities for the Procedure:
  • Record activity to log book.
Procedure
Procedure:
Rotation of the dechlorination Sodium Bisulfite Pumps is performed at the SCADA workstation. Click here for a SCADA screen view of the Sodium Bisulfite System. Please note: Sodium Bisulfite Pump 1302PMP/MTR3100 is labeled P211 and Sodium Bisulfite Pump 1302PMP/MTR3200 is labeled P-212 on the SCADA screen display.
1.    Login at the SCADA workstation.  The operational status should appear as Remote on the SCADA display screen.  The lead and lag assignments to the Sodium Bisulfite Pumps {tag nos. 1302PMP/MTR3100 & 1302PMP/MTR3200} are switched by pushing the lead/lag button. 
2.    Monitor the new lead pump for operation. If the pump doesn’t start or starts too slowly, perform steps 2.a through 2.c. If the pump operates correctly, go to step 3.
a.    Change the HOA to Hand operation.
b.    Prime the pump by sliding the DeChlor PID Stroke bar to the right.
c.    After the lead pump operation stabilizes, return the HOA to Auto operation.
3.    Confirm other information on the SCADA display screen.
a.    Check the Bisulfite Dosage (GPH) for normal activity. 
b.    Final Effluent Residual levels should be consistent at 0.1 mg/l or less.
c.    Monitor the Sodium Bisulfite Tank levels for available chemical. 
Data & Records Management, Calculations, Forms, Reports
Data & Records Management, Calculations, Forms, Reports:

The stoichiometric relationship for dechlorination with sodium bisulfite indicates 1.46 parts SBS and 1.38 parts alkalinity (as calcium carbonate) are required to remove 1.0 part of chlorine residual.

Limits/Criteria for Data/Results
Limits/Criteria for Data/Results:

Consistent chlorine residual concentrations of 0.1 mg/l or below.

ID
Maintenance Connect